Certain resorcinol derivatives, particularly 4-substituted resorcinol derivatives, are useful in cosmetic compositions for hair and skin benefits among others. Resorcinol derivatives are described in many publications, including Hu et al., U.S. Pat. No. 6,132,740; European Patent Application EP 1 134 207; and Japanese published patent applications JP 2001-010925 and JP2000-327557. Resorcinol derivatives are known compounds and can be readily obtained, for example, by a method wherein a saturated carboxylic acid and resorcinol are condensed in the presence of zinc chloride and the resultant condensate is reduced with zinc amalgam/hydrochloric acid (Lille. J. Bitter, L A. Peiner. V, Tr. Nauch-Issled. Inst. slantsev 1969, No. 18, 127), or by a method wherein resorcinol and a corresponding alkyl alcohol are reacted in the presence of an alumina catalyst at a high temperature of from 200 to 400° C. (British Patent No. 1,581,428).
Resorcinol derivatives, when incorporated in personal care compositions or when deposited on skin, tend to change color and may change character due to many factors. Without being bound by theory, one hypothesis for the cause of discoloration is due to oxidation. The discoloration of resorcinol derivatives, particularly the 4-substituted resorcinol derivatives useful in skin lightening compositions, is especially distasteful to consumers seeking skin lightening benefits. Many attempts have been made to minimize these drawbacks, but so far with minimal success.
There is a need, therefore, for an agent that will stabilize resorcinol derivatives, particularly 4-substituted resorcinol derivatives, against degradation. In particular, there is a need for an agent that will prevent the esthetically displeasing discoloration of 4-substituted resorcinol derivatives in skin whitening compositions.